Goat Weed Side Effects, Interactions and Warnings

The new-onset tachyarrhythmia and hypomania in this patient may have been related to the effects of neuro- and cardio-excitatory compounds in the herbal supplement preparation or herb-drug interactions in someone predisposed to heart disease and possible mood disorder. The patient attributed the onset of these symptoms to an herbal supplement that he had taken approximately 2 weeks before. The patient reported that he took one pill per day of a product called horny goat weed, an over-the-counter herbal supplement marketed to increase pleasure for men.
- Psychosomatics. 2004 Nov-Dec;45(6):536-7. Tachyarrhythmia and hypomania with horny goat weed.Partin JF, Pushkin YR.

Botanical extracts differ from conventional supplements in that they are complicated mixtures of many bioactive compounds. Here they describe their experience with a traditional Chinese medicinal plant Epimedium sp. (goat weed) to illustrate the scientific challenges of firstly, obtaining a standardized product from a complex mixture and secondly, evaluating that product for preclinical and clinical efficacy. In contrast, to its colloquial name 'Horny goat weed' and Internet advertisements as a herbal 'Viagra' for men, extracts of Epimedium are strongly oestrogenic due to the presence of novel potent phytoestrogens of the prenyl-flavone family.
- Novartis Found Symp. 2007;282:173-88; discussion 188-91, 212-8. Standardization and evaluation of botanical mixtures: lessons from a traditional Chinese herb, Epimedium, with oestrogenic properties.Yong EL, Wong SP, Shen P, Gong YH, Li J, Hong Y.

There are some reports of people experiencing an increase in heart rate, blood pressure and insomnia so caution should be used by those taking other stimulative herbs, supplements or medications.